I am a community maintainer on a couple of small non-public projects. I have recently been amazed at how much more efficient our community-forum works, in particular as a support and feature request forum, when using Vanilla Forums.
The forum is laid in a similar fashion to the StackOverflow website, where posts can be voted up, for visibility and it gives a very good overview for the users and the maintainers.
Vanilla Forums is free, as in GPL v2.
I used to use PHPBB back between 2004-2007, then we switched to what I percieved was the most advanced free forum, Simple Machines. I stayed with SMF for 5 long years, until I decided to drop it, since it is practically not in effective development any longer. As far as I can see, the most advanced and most inviting forum engine at the very moment is Vanilla Forums.
Check out other projects who are using it:
Vanillaforums' own forum: http://vanillaforums.org/discussions
Slicehost - http://forums.gamesalad.com/
Sourcefabric - maintains 4 free software on the same forum http://forum.sourcefabric.org/
Ajaxplorer - see how they are using it for feature requests and user support.
http://ajaxplorer.info/community/forum/
The benefit would be a better interface and easier community interaction for the devs of Subsonic as well as a thrill for the users.
